Atherosclerosis is the leading cause of morbidity and mortality in the Western society. High density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol are good epidemiological predictors of risk for clinical events caused by coronary artery disease. Based on a number of recent studies in both animal models and human samples it is clear that the anti- or pro-inflammatory nature of HDL function and not HDL cholesterol levels is a sensitive indicator of the presence or absence of atherosclerosis. Hypothesis: We hypothesize that specific proteins associated with HDL are the functional determinants of its inflammatory properties and identification of such proteins will result in the development of i) novel biomarkers for the early detection of atherosclerosis, ii) biomarkers for following the efficacy of therapeutic approaches that are based on HDL function, and iii) new strategies for therapeutic interventions of atherosclerosis. Our laboratory utilizes ProteinChip technology coupled with surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to facilitate protein profiling. We have successfully utilized the technology and were the first to report the identification of three panels of biomarkers for the early detection of ovarian cancer. In preliminary serum protein profiling studies using SELDI-TOF-MS, we identified an eight-protein core signature (represented by their m/z peaks) that can be used as a serum biomarker panel for identifying pro-inflammatory HDL in mice. We further demonstrated that Hemoglobin-alpha, Hemoglobin-beta, and group XII PLA2 represent three of the peaks in the eight-protein core signature. In this grant proposal, we propose to i) identify and characterize the remaining five proteins that distinguish pro-inflammatory HDL from anti-inflammatory HDL, ii) determine the biological basis for the differences in Hemoglobin and group XII PLA2, between pro-inflammatory and anti-inflammatory HDL, and iii) determine the utility and function of the new biomarkers in apoA1 mimetic peptide based therapy in mouse models of atherosclerosis. Atherosclerosis is an underlying cause for onset of cardiovascular diseases. The knowledge of protein profiles that distinguish pro-inflammatory HDL from anti-inflammatory HDL will provide will provide new strategies for early detection as well as therapeutic intervention of atherosclerosis.